Between 13:00 UTC 24th November and 09:30 UTC 25th November, the cache for this website was incorrectly caching HTML responses from the forum.
If you were logged in and browsing the forum during this time, our CDN may have cached the HTML pages you were looking at. Your account / login was not compromised and you do not need to reset your password.
Essentially, imagine someone was looking over your shoulder on ukff.com between 13:00 UTC 24th Nov and 09:30 UTC 25th November - whatever pages you viewed might have been cached temporarily and seen by other visitors. This might include your profile or messenger pages as well as topics or posts you viewed.
All caches have been purged and the configuration was fixed at 09:30 UTC 24th November so this issue is no longer occurring.
NOTE: If you did not visit ukff.com while logged in during the time period, your pages will absolutely not have been put into the cache at all and therefore nobody else could have seen those responses.